Further Development on Pollution Free Sealing Systen AIRGUARD
by H. Yoshida / Japan Marine Technologies Ltd.
M. Nishino / Japan Marine Technologies Ltd.
1. Introduction
In recent years, to prevent the sea from oil pollution, higher reliability and safety are demanded on the stern tube seal of oil lubricating system in the world.
It is obviously effective to separate the sea water and oil by the medium of the compressed air for prevention from leakage of the sea water and oil, because the air is harmless to the environment. A pollution free sealing system "AIRGUARD" was developed by installing a convenient air control unit which mounts a flow controller, that is an air regulator of constant flow type, for a simple seal assembly which is similar to the conventional type. After the first ship loaded AIRGUARD system in 1988, more than 80 sets of this system have been installed to various kind of ships and they are satisfactorily working in every oceans.
This paper presents the review of AIRGUARD sealing system in the first place, moreover introduces the further development of the system.
2. Review of AIRGUARD 3AS system
2. 1 Design concept
The pollution free sealing system was designed by mainly three concepts as shown in Fig.1.
Because the seal ring used in water lubricating condition is always apt to get damages compared with that in oil lubricating, seal rings except the aftermost should be kept not to contact with the sea water as much as possible. The first concept was introduced to separate between the sea water and oil by something harmless to the environment, i.e. an air, in the seal chamber.
The radial force loaded on the aftermost seal ring should be usually reduced.
When seal rings are operated under the stable condition which has a constant and small differential pressure in spite of the change of sea water pressure, those shows
